This paper introduce Fractional Delay Filter (FD) into SelfInterference Cancellation based Full-Duplex communication system. The paper explains that an accurate delay of baseband signal in cancellation channel is very important for the performance of self-interference cancellation. It emphasise that a delay other than a phase alignment can extend the cancellation to wideband with reasonable performance. Simulations proved the feasibility of application of FD in self-interference based Full-Duplex system.